Catalyst composition

ABSTRACT

Catalyst compositions for preparing polyketones comprising 
     (a) a Group VIII metal compound, containing at least one ligand capable of coordinating to the Group VIII metal, and 
     (b) a boron hydrocarbyl compound 
     are disclosed, in particular catalyst compositions wherein the boron hydrocarbyl compound is a Lewis acid of the formula BXYZ where at least one of X, Y and Z is a monovalent hydrocarbyl group. A preferred catalyst composition comprises a palladium complex and B(C 6  F 5 ) 3 .

This is a divisional of co-pending Application Ser. No. 08/468,930 filedon Jun. 6, 1995; which is a divisional of application Ser. No.08/222,465 filed on Apr. 1, 1994, now U.S. Pat. No. 5,468,708.

The present invention relates to novel catalyst compositions suitablefor use in preparing polyketones.

It is known to produce polyketones, which are linear alternatingpolymers of (a) one or more olefins and (b) carbon monoxide, by a liquidphase process in which the olefin(s) and carbon monoxide are polymerisedtogether in methanol, ethanol or propanol solvent in the presence of apalladium catalyst. Such a process, which is disclosed in more detail infor example EP 121965 and EP 314309, typically employs a catalystderived from (a) a palladium compound (b) a source of an anion which iseither non-coordinating or only weakly coordinating to palladium and (c)a bisphosphine of formula R¹ R² P--R--PR³ R⁴ where R¹ to R⁴ areindependently aryl groups which can optionally be polar substituted andR is a divalent organic bridging group such as--(CH₂)_(n) -- (n=2 to 6).The source of the anion is typically its conjugate acid.

It is furthermore known from EP-A-246683 that polyketones can also beprepared if component (b) in the catalyst is replaced by tin chloride orgermanium chloride. Such salts of a strong acid and a weak base areelectron acceptors, and thus "Lewis" acids.

EP-A-508502 discloses catalyst compositions comprising:

a) a Group VIII metal compound,

b) a Lewis acid of the general formula MF_(n) in which M represents anelement that can form a Lewis acid with fluorine, F represents fluorineand n has the value 3 or 5, and

c) a dentate ligand containing at least two phosphorus-, nitrogen- orsulphur-containing dentate groups through which the dentate ligand cancomplex with the Group VIII metal.

A problem with the prior art catalyst compositions is to improve theirreaction rate.

It has now been found that high reaction rates can be obtained usingcatalyst compositions based upon Group VIII metal compounds inconjunction with specific boron compounds.

According to the present invention there is provided a catalystcomposition for preparing polyketones comprising:-

(a) a Group VIII metal compound, containing at least one ligand capableof coordinating to the Group VIII metal and

(b) a boron hydrocarbyl compound preferably a Lewis acid of the formulaBXYZ where at least one of X Y and Z is a monovalent hydrocarbyl group.

A further advantage of the present invention is the ability tosignificantly reduce or totally eliminate the need to use protonic acidsespecially those having a low pKa e.g. less than 2 although smallquantities of water can be tolerated. It is thought that if residualquantities of such acids are retained in the polyketone, the thermalstability of the polyketone is reduced.

The term polyketone is used herein to mean an interpolymer of one ormore olefins with carbon monoxide. The idealised structure of such amaterial would be a polymer of strictly alternating olefin and carbonmonoxide units. Although polyketones prepared according to the presentinvention correspond to this idealised structure, it is envisaged thatmaterials corresponding to this structure in the main but containingsmall regimes (i.e. up to 10 wt %) of the corresponding polyolefin alsofall within the definition.

Considering next the feedstocks for the polymerisation, it is believedthat any source of carbon monoxide can be used. Thus the carbon monoxidemay contain nitrogen, inert gases and hydrogen.

Any olefin can in theory be used although the best reaction rates areobtained when either ethylene or a mixture of olefins which includeethylene, e.g. ethylene/propylene, ethylene/butylene, ethylene/hexeneand the like, is used. The lower rates obtained in the absence ofethylene should not be construed as indicating that the process can beused only with any ethylene feedstock since other olefins such aspropylene, 4-methylpentene-l, styrene, acrylates, vinyl acetates and thelike all undergo reaction to some extent.

The catalyst compositions of the present invention comprise a Group VIIImetal compound. The Group VIII metals are iron, cobalt, nickel,ruthenium, rhodium, palladium, osmium, iridium and platinum. Palladiumis particularly preferred as the Group VIII metal.

The Group VIII metal compound also contains at least one ligand capableof co-ordinating to the Group VIII metal. Examples of such ligands arephosphorus-, arsenic-, antimony-, nitrogen-, and sulphur-donor ligands,preferably phosphorus-donor ligands e.g. phosphines, phosphinites,phosphonites or phosphites, preferably phosphines. Where phosphines areused, these can be mono-dentate or bidentate. Useful monodentate ligandsare of the formula PR₁ R₂ R₃ where R₁ R₂ and R₃ are independently anoptionally substituted alkyl or aryl group e.g. C₁ -C₆ alkyl, phenyl,anisyl, tolyl. It is preferred that R₁ =R₂ =R₃ ; preferred monodentatephosphines are PPh₃, PMe₃, PEt₃ and P(n-Bu)₃. Alternatively bidentatephosphines can be used especially phosphines of the formula R₄ R₅ P--R₈--PR₆ R₇ where R₄, R₅, R₆ and R₇ may be the same or different and allhave the same definition as the groups R₁, R₂, R₃, and R₈ is a divalentorganic group such as --(CH₂)_(n) --where n=2 to 6. Examples of suchbidentate phosphine are 1,3-bis (diphenylphosphino)propane (dppp);1,2-bis(diphenylphosphino) ethane (dppe);1,4-bis(diphenylphosphino)butane (dppb) and 1,3-bisbis(2-methoxyphenyl)phosphino!propane.

The Group VIII metal compound containing such a ligand can be added tothe reaction medium either in a preformed state or it can be generatedin situ by adding a Group VIII metal precursor and the ligandseparately, preferably simultaneously. Such Group VIII metal precursorswould suitably be simple binary compounds e.g. palladium chloride,palladium acetate. A preferred group VIII metal compound isPd(PP)(acetate)₂ where PP is a bidentate ligand as defined above e.g.dppp.

In addition to the ligand capable of co-ordinating to the Group VIIImetal, the Group VIII metal compound will preferably comprise othergroups bonded to the Group VIII metal; these groups may derive from anyGroup VIII metal precursors that have been used in generating the GroupVIII metal compound. Such groups are suitably halides, especiallychloride; acetate, trifluoroacetate, tosylate, nitrate, sulphate,acetylacetonate, cyanide, preferably acetate.

In addition to the Group VIII metal compound, the catalyst compositionsof the present invention also comprise a boron hydrocarbyl compound forexample a boron alkyl or boron aryl compound. In particular the Boronhydrocarbyl compound can be a Lewis acid of the formula BXYZ where atleast one of X Y and Z is a monovalent hydrocarbyl group. Where any oneof X Y or Z is a monovalent hydrocarbyl group, it is suitably an alkylfor example a C₁ -C₆ alkyl group, or an aryl group for example, asubstituted or unsubstituted phenyl group for example C₆ H₅ or C₆ F₅.Other suitable monovalent hydrocarbyl groups are m,m-C₆ H₃ (CF₃)₂, CF₃and C₂ F₅. It is to be understood that two or three of the groups X, Yand Z can together form bi or trivalent groups respectively. At leastone of X, Y and Z is a monovalent hydrocarbyl group; however, it ispreferred that at least two, preferably three, of X, Y and Z are eachmonovalent hydrocarbyl groups. Suitable examples of such Lewis acids areBMe₃, BEt₃, B(C₆ H₅)₃, B mm-(CF₃)₂ C₆ H₃ !₃, B(mesityl)₃, B(p-FC₆ H₄)₃,B(m-CF₃ C₆ H₄)₃ and B(C₆ F₅)₃, preferably B(C₆ F₅)₃. Where one or moreof X, Y and Z is not a hydrocarbyl group, it is suitably a OH, OR orhalide group preferably a halide group for example fluoride, chloride orbromide especially fluoride. Examples of compounds where one of X, Y, Zis a group other than a hydrocarbyl group are boronic acids of theformula RB(OH)₂ where R is a hydrocarbyl group e.g. PhB(OH)₂, andhydrocarbyl 1,3,2-benzodioxaboroles.

Other suitable boron hydrocarbyl compounds for use in this invention areborate salts of the formula MBR₄ where M is an alkali metal e.g. Li, Na,and R is a hydrocarbyl group e.g. C₆ H₅, C₆ F₅ and substitutedanalogues. For example a suitable compound could be LiB(C₆ F₅)₄ orNaB(C₆ H₅)₄.

The boron hydrocarbyl compound for example the Lewis Acid BXYZ is addedto the reaction medium in an amount such that the Group VIII metal:Boron ratio is in the range 10:1 to 1:200 preferably 1:1 to 1:100 morepreferably 1:5 to 1:70 e.g. 1:50.

The catalyst compositions can be used in either the gas-phase or theliquid-phase. It is to be understood that the term liquid phase alsoincludes slurry-phase where the polyketone product is insoluble in thereaction solvent. Where the catalyst compositions are used in the liquidphase, any suitable solvent can be used. Examples of such solvents areketones (e.g. acetone), ethers, glycol ethers, chlorinated solvents(e.g. chloroform, dichloromethane), hydrocarbon solvents (e.g.cyclohexane, toluene), methanol and ethanol. A particularly preferredsolvent is any olefinically-unsaturated hydrocarbon especially wheresuch a hydrocarbon is also a reactant in the polymerisation reaction.Examples of such olefinically-unsaturated hydrocarbons are C₃ -C₁₀olefins (preferably C₃ -C₆ olefins e.g. propylene, n-butene, isobutene,and n-hexene) and styrene. A preferred olefinically-unsaturated olefinas solvent is propylene. It is a feature of the present invention thatnonalcoholic solvent systems can be used where necessary. Alcoholimpurities in the final polymer can be undesirable where the polymer isto be used for food packaging since alcohols are usually toxic. Thesolvents may contain small quantities of water for example up to about0.5% wt/wt. Where the reaction is carried out in the gas phase, smallquantities of water may be added. Where water is present, it ispreferably present in an amount of at least 4 moles per mole of boron.

The polymerisation process is suitably carried out at a temperature inthe range 20° to 150° C. preferably 50° to 120° C. and at elevatedpressure, (e.g. 1 to 100 bars). The over pressure of gas is suitablycarbon monoxide or carbon monoxide and olefin, if the olefin is gaseousunder the reaction conditions. It is possible to operate thepolymerisation process either batchwise or continuously.

In a further aspect of the present invention there is provided apolyketone wherein at least 30, preferably at least 40 more preferablyabout 50 mole % of the end groups are aryl or substituted aryl groupsfor example phenyl or substituted phenyl preferably C₆ F₅ groups.

The following Examples illustrate the present invention.

Experimental

Toluene and diethylether were distilled from sodium. Dichloromethane wasdistilled from calcium hydride.

Pd(PPh₃)₂ (COCH₃)Cl was prepared in 97% yield by the addition of acetylchloride to Pd(PPh₃)₄ according to the method described by Fitton et al,(Chem. Comm., 1968, 6.) Pd(PPh₃)₄ was synthesised according to themethod described by Coulson (Inorganic Syntheses 1970, 13, 121).

EXAMPLE 1

(a) Preparation of Pd(dppp)(COCH₃)Cl Pd(PPh₃)₂ (COCH₃)Cl (6.1319 g, 8.6mmol), 1,3-bis(diphenylphosphino) propane (dppp) (3.7711 g, 9.1 mmol)and toluene (100cm³) were mixed and the resulting mixture was stirredunder nitrogen for 1 hour. Diethylether (100cm³) was added and themixture was filtered. The solid product was washed with diethylether(20cm³) and dried in vacuo to give Pd(dppp)(COCH₃)Cl (4.8521 g, 8.1mmol). Yield=94%.

(b) Polymerisation

Tris(pentafluorophenyl)boron, (0.0436 g, 0.085 mmol) was dissolved indried, degassed dichloromethane (100cm³) and transferred to a 300cm³Autoclave Engineers reactor under nitrogen. The stirred reactor contentswere pressured to 45 barg with a 1:1 mixture of carbon monoxide andethylene and heated to 70° C. A solution of Pd(dppp)(COCH₃)Cl (0.0154 g,0.026 mmol) in dried, degassed dichloromethane was added to the reactorand the pressure was adjusted to 50 barg by addition of 1:1 CO/C₂ H₄.During the subsequent reaction, a pressure of 50 barg was maintained bythe addition of 1:1 CO/C₂ H₄. Three hours after the addition of thepalladium complex to the reactor the reaction was stopped by cooling themixture and venting the gaseous components. The alternating ethene/COcopolymer was collected by filtration and dried in vacuo. Yield=11.502g. This represents a productivity of 1397 g/gPd/h.

EXAMPLE 2

(a) Preparation of Pd(dppp)(OAc)₂ Palladium acetate (1.000 g,4.4563×10⁻³ M) was dissolved in HPLC-grade acetone (100cm³) and thesolution was stirred for 2 hours and then filtered. To the filtrate asolution of dppp (1.8390 g) in HPLC-grade acetone (25cm³) was slowlyadded over a period of 1/2 hour. Soon after needle-like crystals beganto form; diethyl ether (25cm³) was then slowly added and the mixtureallowed to stand for 1/2 hour. The resultant pale-yellow precipitate wasfiltered, washed with toluene (5 ml) and dried in vacuo to give aPd(dppp)(OAc)₂ (2.146 g).

(b) Polymerisation B(C₆ F₅)₃ (0.2407 g) was weighed in air into a driedSchlenk tube and a solution in dried dichloromethane (100cm³) wasprepared under nitrogen. This solution was then transferred to a 300 mlstirred autoclave and 25 g propene added.

The autoclave was then pressurised to 30 BarG with the reaction gas(premixed CO/C₂ H₄, 50/50 v/v) and heated to 70° C.

A solution of Pd(dppp)(OAc)₂ (0.0154 g) in dried dichloromethane (10cm³)was injected into the autoclave, which was then pressurised to 50 BarG(the reaction pressure) with CO/C₂ H₄.

The reaction was run for 1 h. and 22.495 g polyketone recovered. Thisrepresents a productivity of 8730 g/gPd/h.

We claim:
 1. A polyketone wherein at least 30 mol % of the end groupsare aryl or substituted aryl groups.
 2. A polyketone as claimed in claim1 wherein the aryl or substituted aryl groups are phenyl or substitutedphenyl groups.
 3. A polyketone as claimed in claim 2 wherein thesubstituted phenyl groups are C₆ F₅.
 4. A polyketone as claimed in claim4 wherein about 50 mol % of the end groups are aryl or substituted arylgroups.
 5. A polyketone as claimed in claim 4 wherein the aryl orsubstituted aryl groups are phenyl or substituted phenyl groups.
 6. Apolyketone as claimed in claim 5 wherein the substituted phenyl groupsare C₆ F₅.
 7. The polyketone as claimed in claim 1 wherein the arylgroup is comprised of a C₁ -C₆ alkyl group.
 8. The polyketone of claim 1wherein substituted aryl is selected from the group consisting of m,m-C₆H₃ (CF₃)₂, CF₃, and C₂ F₅.